This invention relates in general to the radiological arts. More specifically, it provides a semi-automated process for determining the volume of a tumor within a body organ. The invention has particular application to cancer treatment programs and research.
With the now widespread use of CT scanners, it has become increasingly recognized that rapid and accurate organ and tumor volume determinations from Computed Tomography (CT) image data can be of great value in radiotherapy treatment planning. See for example, the following publications - Hobday P, Hodson NJ, Husband J, Parker RP, MacDonald JS, "Computed tomography applied to radiotherapy treatment planning: techniques and results" Radiology 1979; 133:477-82; and Van Dyk J, Battista JJ, Cunningham JR, Rider WD, Sontag MR, "On the impact of CT scanning on radiotherapy planning" Comput Tomogr 1980; 4:55-65. Tumor volume determinations are also important for radiation dose estimates for normal and tumor issues in radiolabeled antibody cancer therapy. See for example the following publications - Leichner PK, Klein JL, Garrison JB, et al "Dosimetry of .sup.131 I-labeled antiferritin in hepatoma: a model for radioimmunoglobulin dosimetry" Int J Radiat Oncol Biol Phys 1981;7:323-33; Leichner PK, Klein JL, Siegelman SS, Ettinger DS, Order SE "Dosimetry of 131I-labeled antiferritin in hepatoma: specific activities in the tumor and liver" Cancer Treat Rep 1983;67:647-58; and Leichner PK, Klein JL, Fishman EK, Siegelman SS, Ettinger DS, Order SE "Comparative tumor dose from .sup.131 I-labeled polyclonal anti-ferritin, anti-AFP, and anti-CEA in primary liver cancers" Cancer Drug Delivery 1984; 1:321-8. Such volume determinations are also important for the assessment of tumor response to new treatment modalities. See for example the following publication--Order SE, Klein JL, Leichner PK, et al, "Radiolabeled antibodies in the treatment of primary liver malignancies" In:Levin B, Riddell R, eds. Gastrointestinal cancer, New York: Elsevier-North Holland, 1984;222-32.
Volume computations from CT have been investigated by several authors using a variety of methods. For example, see the following publications--Heymsfield SB, Fulenwider T, Nordinger B, Barlow R, Sones P, Kutner M. "Accurate measurement of liver kidney, and spleen volume and mass by computerized axial tomography" Ann Intern Med 1979;90:185-7; Henderson JM, Heysfield SB, Horowitz J, Kutner MH, "Measurement of liver and spleen volume by computed tomography" Radiology 1981; 141:525-7; Moss AA, Cann CE, Friedman MA, Marcus FS, Resser KJ, Berninger W., "Volumetric CT analysis of hepatic tumors" J Comput Assist Tomogr 1981;5:714-8; Moss AA, Friedman MA, Brito AC, "Determination of liver, kidney, and spleen volumes by computed tomography: an experimental study in dogs" J Comput Assist Tomogr 1981; 5:12-4; Breiman RS, Beck JW, Korobkin M, et al, "Volume determinations using computed tomography. AJR 1982; 138:329-33; Oppenheimer DA, Young SW, Marmor JB, "Work in progress, serial evaluation of tumor volume using computed tomography and contrast kinetics" Radiology 1983; 147:495-7; Reid MH, "Organ and lesion volume measurements with computed tomography" J Comput Assist Tomogr 1983;7:268-73.
Moss et al [Moss AA, Cann CE, Friedman MA, Marcus FS, Resser KJ, Berninger W., "Volumetric CT analysis of hepatic tumors" J Comput Assist Tomogr 1981;5:714-8]have described a computer program for calculating the mean CT number of normal liver tissue in each CT "slice" and obtaining total liver volume by summing over all CT slices containing liver. Tumor volume in each slice was obtained by subtracting a Gaussian distribution of CT numbers for normal liver from the bimodal CT number distribution for the whole liver. The results from all slices were summed to obtain partial tumor and liver volumes for each patient.
It is known to determine tumor and liver volumes from sets of manually contoured CT slices. However, as practiced in the prior art, such determinations are time-consuming and labor-intensive. A radiologist must outline with a grease pencil regions of interest (ROI) corresponding to tumor and normal liver on patients' CT films. These contours are then digitized, the areas computed by numerical integration, and multiplied by slice thickness to obtain tumor and normal liver volumes for each slice. Total volume is obtained by summing over all slices. In spite of the fact that such methodology is extremely cumbersome, it was carried out for several years (1979-1984), and clinically relevant and important results were obtained and published in scholarly journals. The method of Moss et al also required manual contouring, directly on a video monitor, and slice-by-slice analysis of patients' CT scans.
To handle the increased number of patients due to expansion of the radiolabeled antibody treatment programs, it became evident that further automation was required to provide clinicians with timely information about tumor response to therapy and for radiolabeled antibody treatment planning.